Motor control problems such as shaking, rigidity, slowed movement and poor balance are often the first and most troubling symptoms of Parkinson’s disease. In later stages, patients tend to develop a variety of cognitive and mood problems, including depression, apathy, slowed thinking, confusion, impaired memory and trouble sleeping.

Drugs can help with motor control, but can worsen some symptoms and are less effective in the later stages of Parkinson's.

An alternative is deep brain stimulation (DBS), an invasive surgery. There are two sites on the brain where deep brain stimulation is done, and scientists were unsure which was best. A new study finds them to be similarly effective.

When patients receive DBS for Parkinson's, a neurosurgeon precisely guides a very fine wire into one of two deep brain regions involved in motor control, the subthalamic nucleus (STN) or the globus pallidus interna (GPi). An implantable battery is used to send a finely tuned electrical current to stimulate the brain. Often, dramatic improvement of motor symptoms can be observed in the operating room when the wire is properly placed and the stimulator turned on. Stimulation on both sides of the brain, or bilaterally, is considered most effective.

There is a widely held view that of the two techniques, STN DBS is more effective at controlling motor symptoms but more likely to aggravate non-motor symptoms. The new study – the largest most comprehensive study ever done of patients receiving bilateral STN DBS or GPi DBS — challenges these ideas.

"We found that motor outcomes between the two groups were not significantly different. Meanwhile, there were very modest differences in mood and cognitive function between the two groups," said one of the study's lead investigators, Dr. Kenneth Follett, chief of neurosurgery at the University of Nebraska Medical Center in Omaha. "Physicians and patients can have confidence in both types of DBS, and can make their choice based on the constellation of motor and non-motor symptoms that determine quality of life in Parkinson’s disease."